High-frequency electrical-oscillation generator.



L. DB FOREST. 7 HIGH FREQUENCY ELECTRIGAL OSCILLATION GENERATOR.

APPLICATION I ILED F238, 1908 Patented Dec. 20, 1910.

2 BHEIITSSHEET 1 L, DE FOREST.

EIGE FREQUENCY ELECTRICAL OSCILLATION GENERATOR.

APPLIGATIQN FILED FEB. 8, 1908.

Patented Dec. 20, 1910.

2 SHEETS-SHEET 2.

UNITED STATES. PATENT HIGH-FREQUENCY ELECTRICAL-OSCILLATION GENERATOR.

Specification of Letters Patent. Application filed February 8, 1908. Serial No. 4 14,97 6.'

OFFICE.

Patented'Dcc.

To all'whom it may concern:

Be it known that I, Len nn- Founsr, a citizen' of the United States, and a resident of New- York, in the county of "New York and State-of New 1 ork, have invented a new and.

useful Im roveincnt in High-Frequency Electricalscillation Generators, of which the-following is a specification.

My invention relates to high frequency electrical oseillationgenerators and more part cularly to gencratorsof undamped or L- practically continuous electrical oscillations force connected to said electrodes through conductors of high ohmic or inductive resistance A circuit of this type is subject to certa n defectsdue to the irregularities in the burning of the arc whichproduce corresponding variations in the oscillations generated therein and which sometimes result in the sudden extinguish'ment of the arc and in the stoppage of said oscillat ons.

The object of the present invention is to provide a circuit for developing undalnped high-frequency electrical oscillations which shall not requireau oscillating arc and which therefore shall be'rcgular and constant in operation. This object may be accomplished by substituting for the arc'electrodes of'the prior art a properly conducting heat-rcsistiug medium, such as a conductor of the second class, preferably of short length, of relatively low resistance,

and of considerable current carrying capacity. For this purpose a Variety of substances may be employed, such as oxide of the zirconium group, zirconia, glucina, yttria, thoria, etc., commonly called the rare earths, a non-conductor such as pipe-clay or porcelain coated with such oxids, porous substances such as fire-clay il'npregnated with such oxids. asbestos or mineral wool alone or in'i 'iregnated with one 'or more of the rare earths, .highresistance graphite, or

hard carbon filaments, such as incandescent lamp filaments. These substances when cold are either non-conductors or else are of too high a resistance to permit of thegcneration of high frequency oscillations when'inserted in-an oscillation circuit. For this reason some means must be provided for heating the substance and thereby red'ucingits re .sistance. While'various heating means may be employed, I' prefer to make use of the source of -electrical energy, preferably a source of direct current, which-energizes the oscillation ,circuit for heating the conduct'or of the second class whichl substit-ute for .the oscillating arc.

One important feature of my invention consists in the fact that my oscillation circuitis an electrically closed circuit, and'in fact, except for the condenser, is physically closed as distinguished from the oscillation circuits" of the. prior art,.w hich are not closed but arebioken by a gap. between. the arcelectrodes. -An oscillation circuit compris mg a condenser and an unbroken circuit 'which may include an inductance connecting the terminals of said condenser possesses ma y advantages over the oscillation circuits in use today, in that therebya-imich greater constancy and continuity of operationis secured.

* The drawings which accompany and form a part of the present specification illustrate in diagram the application'to-a space telephone system of several arrangements of apparatus'and circuits whereby my invention has been realized in practice; but: it is to be understood that I have shown ,in' said drawings only a few of the numerousembodiment-s of my invention for the purpose of explaining the principle thereof and that various modifications maybe niade both-in the apparatus and in. the circuit arrangements" without departing froin said principle. r

In the drawings Figure 1 represents a space telephone system energized by;onc :form of the oscillation circuit which constitutes the subject matter of-the present application. F ig. 2 shows a modification of the oscillation circuit having a non-condu'ctor coated with a conductor of. the second class. Fig. 3 shows a further modification in which the oscillation circuit is provided with means for forcinga suitable gas or vapor through a body of porous material coated or impregnate with a conductor of the second class. Figs; 4 and -5 re resent other modifications. in which short. engt hs of hard carbon filaments are 'mploye substitute for. the oscillating arc. a In the figures, Vis an elevated transmit'-. 'ting conductor. 1 5 ;M is an oscillation transformer, of which the primary andsecondary respectivelyare shown'I aIId I v I '-K is a'. microphone transmitter.

E is an earth connectionr (lis a condenser.

rent.. v .L, L are nductiveresistances.

RL1sa non-1n uctive resistance.

[In-Fig. 1 A a d B are fixed terminals 6a 1 copper, carbon or other Suitable material, I

and D is a.finger,- which maybe of copper, secured to thefc'ollar D which may be moved over the terminal Iiby means of the insulat- 2 ing handle N. F represe'nts alump of one of the r-are earths, preferably thorium oxid orqthor'ia, or asbestos or mineral wool which fma be in; e nate with. 0 e'ofthe rare earths. g

hydrogen or a gas containing hydrogen.

The operation is as follows: The finger D is brought in contact with the terminal. A and slightly Withdrawn so as to create an I." electric-arc. When thisvarc-is aintained ina suitable atmosphere, the c" nit C D D A I gives rise to practically continuous or undamped elec'tricahoscillations. The sub- 5 stance F soon becomes heated to incandes- 'cence and thereby becomes highly conducting. The result is that the current in theoscillation circuit is shunted from the elec trodes D and A and passes through the sub-' stance F which is maintained in good co'ntact'with the terminals A and B. The arc is now; extinguished and the circuit continues ,to develop high frequency electrical oscillations which are practically continuous or -undamped and which, are. much more regular in frequency and constant in amplitude than those developed by the oscillating arc circuit.

high frequency, pass almost entirely over the surface'ofthe substance F on account of the well known phenomenon known as the skin-efiect. .It is preferable that the sub-' stance'F shown in Fig. 1 and the various modifications thereof shown in Figs. 2 to 5, inclusive, be so designed as to have a resistance varying betweenthe limits 30 to 50 ohms and-to have a current carrying capacity of from two to five amperes.

In Fig. 2, F represents a tube or rod of pipe clay, or porcelain or other suitable heatresisting non-conductor coated with one of,

the hereinbefore mentioned conductors of the second class. The member F is secured to the fixed terminal A of the oscillation circuit. which terminal may be copper. The v G is a; generator, preferably of direct cur-" v I resents. conventionally a casing ,inclos1n'g the' substance so that the same may be surrounded with an atmosphere of These oscillations,.-being of veryfingenJ" isihinged at j t o'the movable terminal- J which is secured to the guide J .and is adapted-to be moved therethrough by the insulating handle N. v I

The operation is as follows: The finger J tween "A and J.-. Thecircuit C J A. I, giv'esrise to undamped high frequency electrical oscillations, and as-soon as the con-' ductor of the second class becomes heated and its'resistance'is sufliciently reduced, the

arc is extinguished automatically and the oscillations pass along. the surface of: the flmeniber F I '70 is movedv along the member'F until conj tacts the termi-naljA and is then slightly Withdrawn so as to start an electric are he- .In'Eig. 3- theinember 'F" is shown as a tube of porous material such as fire .c'lay coated or impregnated with 'a'conduct'or of the second class and secured to a. reservoir which a suitable gas may be forced under high pressure. This gas will escape through the poresof the member F and thus surround the are which is, created between J and Afwith the atmosphere requiredifor .1 5 A provided with an inlet K through the production of oscillations in the oscillation circuit. After the are has been. ex-

tinguished and the oscillations take place over the surface of the member F" in the manner above outlined in connection with the member F of Fig. 2,\ this gas serves to surround the highly heated surface of the" member F" and thereby assists maintaining the oscillations. By employing the ar- F and F may consist 'of-graphit which when heated by the'arc has a sufficient sur- H face conductivity to permitof the creation of high frequency oscillations in theoscillation circuit andwhich has a sufficiently high inter r al" resistance to prevent the shunting of the. current from the generator Gth'rough' its interior portions. I 1 In Fig. 4 P represents a short len th of hard carbon filament such as an ordinary incandescent lamp filament, andas shown, a

,numberof such filaments may be inolosed within the evacuated tube O'Iand connected with the condenser C and inductance I 'by the leading in wires P. As shown in 'Fig. 5, a plurality of evacuated tubes O' .each containing one filament P may be employed in place of the multiple filament arrangement shown in Fig. 4. I

' and substantially constant The operation of the arrangements shown in Figs. 4 and 3 is as follows: The filaments P are heated to incandescence by the current from the generator G, whereupon it said filaments are of sutliciently short length and adequate current carrying capacity, the circuit C 1 I, will give rise to practically continuous or undampened high frequency electrical oscillations of uniform frequency amplitude.

The well known rules for constructing singing are or oscillation are circuits should be followed in the construction of the oscillation circuit described herein. The generator G is preferably a direct current generator capable of developing 2 rolls, the impedances L. L are sufficiently high to resist sudden changes of current and the capacity (land inductance I should be so designed with respect to the resistance of the oscillation circuit that the latter will be highly oscillatory.

The function of the transmitter K connected in the antenna ata point having practically zero potential with respect to earth is to vary the oscillations developed by the oscillation circuit in said antenna in accordance with the yibrations'of the air accompanying articulate speech. as more fully explained by me in connection with Fig. l of my Letters Patent Yo. 836,015 dated November 13, 1906.

It will of course be understood that the limited in its application to wireless teleplr ony or to wireless telegraphy, but may be employed wherever it is desired to create lndamped high frequency electrical oscillations of great uniformity and regularity.

' I claim: g

.1. The combination with a source of electric: l tion circuit comprising a capacity. an inductance and a non-conductor coated with a conductor of the second class. said coated non-conductor being associated with a circuit bridged' across the terminals of the energy source and the capacity.

2. The combination witha source of electrical energy of a high frequency oscillation circuit comprising a capacity, an inductance and a non-conductor coated with a conduco cillation circuit hereinafter claimed is net energy of a highfrequency oscilla -.l. The combination with a source of electrical energy of a high frequency oscillation -rircuit comprising a capacity, an inductance l l l l and a i1o]1- .'onductor coated with an oxid of the zirconium group, said coated non.conductor being associated with a circuit bridged across the terminals of the energy source and the capacity and means for heating the latter.

5. The combination with a source of electrical energy of a high frequency oscillation circuit comprising a capacity, an inductance and a non-conductor coated with an oxid of thorium, said coated non-conductor being associated with a circuit bridged across the terminals of the energy source and'thc capacity.

(5. 'The combination with a source of electrical energy of a high frequency oscillation circuit comprising 'a capacity, an inductance and a non-conductor coated with an oxid of thorium, said coated non-conductor being associated with a circuit bridged across the terminals of the energy source and. the capacity and means for heating the latter.

7. The con'il'iination with a source of electrical energyof a high frequency oscillation circuit comprising a capacity, an inductance and a conductor of the second class, and meansfor creating an electric arc in juxtaposition tosaid conductor. S. The combination with a sourceof electrical energy of a high frequency oscillation circuit containing a capacity, an inductance, a fixed terminal .and a movable terminal forming a bridge across the terminals of the energy source and the capacity, and a conductor ofthe second class in contact. with said terminals.

9.. The combination With asource of electrical energy of a high frequency oscillation circuit comprising a capacity, an inductance and two terminals arranged in a circuit bridging the terminals of the energy source and the capacity, a conductor of the second class arranged between said terminals and means-whereby an electric arc may be created between said terminals to heat said conductor. y

10. The combination with a source of electrical energy of a high-frequency oscillation circuit comprising a capacity, an inductance and a hollow porous non-conductor coated with a conduetorof the second class, said coated non-conductor being associated with a circuit bridging the terminals of the energy source and the capacity; and means for forcing a gas containing hydrogen through said hollow nonconductor.

11. The combination with a source of elec trical energy of a high frequency oscillation circuit comprising a capacity, an inductance and a porous non-conductor coated with a eondiictor of the second class, said coated non-conductor being associated with a circuit bridgin the terminals "of the energy for surrounding said conductor with an;

source and the capacity. I atmosphere containing hydrogen. I v

, 12. The combination-With a source of elec- In testimony whereof, I have hereiinto trical energy of'a high frequency oscillation subscribed my name this 27 day of Jan. 5 circciuit comprisilng a capacity, an indugtance 1908.

an a orouseat-resistin non-con uctor A 1 v coated gith a. conductor of %he second class, LEE DE FOREST said coated'non-conductor being associated Witnesses:

with a circuit bridging the term nals of the f 'SADIE LIULLANE 10 energy source and the capacity, and means 1 ISAB L LEVISON. 

